golang mission

main.go

package main

// See comments in main(), this is written in Go.

import (
	"log"
	"sort"
)

func makeMap(items []string) map[string]int {
	itemsToTheirCount := make(map[string]int)
	for _, item := range items {
		if value, mapContainsItem := itemsToTheirCount[item]; mapContainsItem {
			itemsToTheirCount[item] = value + 1
		} else {
			itemsToTheirCount[item] = 1
		}
	}
	return itemsToTheirCount
}

func makeCustomerMaps(shoppers map[string][]string) map[string]map[string]int {
	itemCounts := make(map[string]map[string]int)
	for shopperName, itemsList := range shoppers {
		itemsMap := makeMap(itemsList)
		itemCounts[shopperName] = itemsMap
	}
	return itemCounts
}

func alikeness(s1items map[string]int, s2items map[string]int) int {
	score := 0
	for s1ItemName, s1ItemCount := range s1items {
		if s2itemCount, mapContainsItem := s2items[s1ItemName]; mapContainsItem {
			score = score + s1ItemCount + s2itemCount
		}
	}
	return score
}

func updateRelationsMap(relationsMap *map[string]map[string]int, s1 string, s2 string, score int) {
	if _, mapContainsKey := (*relationsMap)[s1]; !mapContainsKey {
		(*relationsMap)[s1] = make(map[string]int)
	}
	if _, mapContainsKey := (*relationsMap)[s2]; !mapContainsKey {
		(*relationsMap)[s2] = make(map[string]int)
	}
	(*relationsMap)[s1][s2] = score
	(*relationsMap)[s2][s1] = score
}

func main() {
	testShoppers := map[string][]string{
		"fred":  []string{"Banana", "Coffee", "Coffee", "Energy Drink"},
		"ralph": []string{"Cup Cakes", "Cigarettes", "Wine", "Lighter"},
		"jeff":  []string{"Coffee", "Fountain Drink", "Gum", "Lighter", "Propane"},
		"jake":  []string{"Candy Bar", "Energy Drink"},
		"brian": []string{"Coffee", "Toy Robot"},
	}

	// Map a customer to the items in their basket and its count.
	// We will use this map to calculate a "distance" between
	// a customer and every other customer given their items.
	// For fred, this would be:
	// "fred" : {
	// 	"Banana":1,
	// 	"Coffee",2
	// 	...
	// }
	itemCounts := makeCustomerMaps(testShoppers)

	// This map will map a customer to a list of other customers
	// who are mapped to their "alikness".
	// For example, fred:
	// "fred": [
	// 	{ "brian", 3},
	// 	{ "jake", 2 },
	// 	{ "jeff", 3 }
	// ]
	// This means fred is most alike to brian and jeff equally.
	relationsMap := make(map[string]map[string]int)

	customerNames := make([]string, 0)
	for key := range itemCounts {
		customerNames = append(customerNames, key)
	}
	sort.Strings(customerNames)

	// Compare each customer to every other customer,
	// starting the inner loop one ahead to avoid doing duplicate
	// work.
	for index, shopperName := range customerNames {
		for i := index + 1; i < len(customerNames)-1; i++ {
			score := alikeness(itemCounts[shopperName], itemCounts[customerNames[i]])
			updateRelationsMap(&relationsMap, shopperName, customerNames[i], score)
		}
	}

	log.Print("Alikness between customers (higher score means more alike)")
	for key, value := range relationsMap {
		log.Printf("Customer: %s\n", key)
		for key2, value2 := range value {
			log.Printf("\t=> Alikeness with %s\tScore: %d\n", key2, value2)
		}
	}
}